He conducted many Belgian entries in the Eurovision Song Contest and had his own Big band orchestra titled "Francis Bay and His Big Band".
Francis Bay followed musical education at the conservatorium of Mechelen and started his musical career at the orchestra of Paul Godwin.
In 1948 he formed his own orchestra and in the middle of the 50's he became the leader of the orchestra of the National Radio broadcast Institute (NIR).
Francis Bay produced many albums and composed theme songs for game and entertainment programmes on BRT. As conductor of the National Radio and Television Orchestra Francis Bay conducted the orchestra at the Flemish national selection shows Canzonissima.
In 1937, he joined Paul Godwin's Jazz Symphonians, a high-profile light-entertainment orchestra based in the Netherlands, simply "because there was more money to be made".